Question

why do Helium neon and Argon have a zero valency

Answer 1

Originally Answered: Why do helium, argon, neon have zero valency? Basically if an element has 8 electrons in its valence shell or 2 electrons in its only shell like helium it does not require anymore electron as its shell is already completed and hence it neithet loses nor gain electrons.

Answer 2

Helium and argon have zero valancy as helium has 2 electrons which satisfies duplet confguration that is it has its s orbital completly filled  Argon has octate configuration that is 8 electrons it has its s1 s2 p1 s3 p2 orbitals full . These are even known as nobel gases.